Greatly overshadowed by his famous employer, Thomas Edison, Serbian-born inventor and physicist Nikola Tesla is known mostly as the mastermind behind the AC induction motor and the Tesla coil.

While Tesla enjoyed a successful career as an inventor, he displayed many asocial behaviors and didn’t have any documented romantic relationships; he ultimately ended up financially destitute and alone. Having become more eccentric with each passing year, Tesla amassed a list of odd behaviors that accompany his legacy of preternatural brilliance; Tesla truly was an archetypical “mad scientist”. Represented here are both sides of one of the most complex thinkers of our time.

Here are 10 things you might not know about Nikola Tesla.

1. He envisioned the modern day smartphone – in 1909

Attempting to make good on his idea to craft a handheld device that could receive stock quotes and telegram messages via encoded and broadcasted frequencies, Tesla went on to design the very first wireless transmission tower and had it erected in Long Island New York, along with a laboratory facility. Wardenclyffe Tower, so named after the investor, James S. Warden, was meant for trans-Atlantic wireless telephony and broadcasting, but it was never fully functional, and was therefore demolished in 1917.

2. He suffered from oystersaritisphobia – the fear of pearls

Not being able to tolerate even the sight of the gem, Tesla once sent his secretary home to change after she showed up to work donning a strand of Tesla’s much-hated spheres. This is one of many traits –such as being obsessed with the number 3 and being extremely wary of germs- that have given many cause to believe that Tesla suffered from a form of Obsessive Compulsive Disorder.

3. He rarely slept

Tesla claimed to only sleep two hours per night, and was prone to spending two days or more in his laboratory without sleeping at all. Kenneth Swezey, one of the inventor’s friends, confirmed Tesla’s claims. Swezey once recounted a time when Tesla phoned him at 3 a.m.: “I was sleeping in my room like one dead … Suddenly, the telephone ring awakened me … [Tesla] spoke animatedly, with pauses, [as he] … work[ed] out a problem, comparing one theory to another, commenting; and when he felt he had arrived at the solution, he suddenly closed the telephone.” Tesla did admit to dozing every now and again to “recharge his batteries.”

4. He had a photographic memory

Possessing the ability to read books and periodicals while simultaneously committing them to memory served Tesla well; he used all the information he acquired as an internal library, available at his beck and call. As a result, Tesla rarely made drawings of his inventions, but worked from a picture or a memory in his head.

5. He spoke 8 languages

No doubt hastened by his eidetic—commonly known as photographic—memory, Tesla was fluent in 8 different languages: Serbo-Croatian, English, Czech, German, French, Hungarian, Italian and Latin. Linguists refer to such a person as a “hyper polyglot”, or someone who can speak more than six languages with great proficiency.

6. He invented the first hydroelectric power plant

In 1895, along with George Westinghouse, Tesla built the first power plant to tap the hydroelectric potential trapped within Niagara Falls. The Niagara Falls Power Company marked the final victory of Tesla’s Poly-phase Alternating Current (AC) electricity, which powers the world today.

7. He had a death ray

To put it a bit more accurately, Tesla possessed an intricate design plan for a death ray – a particle beam/directed-energy weapon he named “Teleforce” —that was meant to be used during World War One to wipe out whole armies. He described the invention thusly: “[The nozzle would] send concentrated beams of particles through the free air, of such tremendous energy that they will bring down a fleet of 10,000 enemy airplanes at a distance of 200 miles from a defending nation’s border and will cause armies to drop dead in their tracks.” Tesla worked to bring Teleforce to fruition until the day he died.

8. He had a strange relationship with pigeons

While Tesla appears to have been unable to foster feelings for humans and has thus been described as asocial, perhaps his aversion to people had less to do with his lack of emotion and more to do with the fact that they lacked feathers. Like many people do, Tesla would feed the populous gray colored birds at the park. Even after he was too ill to do it himself, he hired others to do it for him. He would often bring sick or injured pigeons back to the hotel where he lived in his later years, and nurse them back to health. He grew especially fond of one little bird, and said this about her; “I loved that pigeon as a man loves a woman, and she loved me. As long as I had her, there was a purpose to my life.”

9. He died broke and alone

A sad, empty ending for a man filled to the brim with brilliance, Tesla died on January 7th, 1943 from coronary thrombosis in the New Yorker hotel room that had served as his home for a decade. The hotel maid discovered his body two days later, after she chose to ignore a “do not disturb” sign placed on his door. Though he sold his AC electrical patents, Tesla died in debt because he self-funded many of his own projects that never ended up seeing the light of day.

10. Many of his inventions remain classified

Upon his death, most of Tesla’s belongings were taken by the Office of Alien Property – even though he was legal citizen of the United States. And by “most”, we mean what has been described as a “railroad boxcar” full of Tesla’s materials. After a time, some items were released to his family, while others ended up in the Tesla museum, located in Belgrade, Serbia (where his ashes are also kept). Some of Tesla’s documents and papers still remain classified, and while people have requested items via the Freedom of Information Act, those items are heavily redacted before their release. As a result, people tend to wonder what else Nikola Tesla had up his sleeve—like a device that would lead to free energy— before his death.